Culverts are commonly used to carry flows in small drainages across roadways and railroads. They are most common in rural applications but are also used in a variety of different ways in urban situations. This course will discuss the appropriate design of culverts. The most obvious requirement for a culvert is to adequately convey the water that reaches the culvert under the roadway without flooding, but appropriate selection of material type including service life is also necessary. The hydraulic design also includes more than just the size of the pipe. The material selection impacts the appropriate friction factor and the inlet configuration can significantly impact the culvert capacity. The impact of the downstream flow conditions also needs to be considered. This course will cover the design of culverts, using the Federal Highway Administration software HY8 as the platform to analyze the hydraulics. It will include a description of the necessary input parameters for HY8 and the likely sources of these parameters. It will also discuss material selection, pipe life, erosion considerations and appropriate minimum and maximum cover conditions. While the course is based on HY8, it is not necessary to download or run the software to take this course. The course uses HY8 as a tool to evaluate a variety of conditions related to culvert hydraulics.
COURSE OUTLINE:
• Important parameters to consider in the hydraulic analysis of a culvert
• Selection of pipe materials and impacts on hydraulics, design life and structural integrity
• Material options – RCP, CSP, CAP, Corrugated plastics
• End treatments, including headwalls, improved inlets, flared end sections and riprap aprons
• Data requirements for using FHWA HY8 software
• Basics of hydraulic analysis using HY8
• Analysis of more complex situations using HY8
• Minimum and maximum cover conditions
• Erosion control upstream and downstream
• Pipe Life
LEARNING OBJECTIVES:
At the conclusion of this course, the user will:
• Understand the material choices available for culverts and the advantages of each option.
• Understand the options available for inlet configurations and the hydraulic impacts of each option
• Understand how FHWA HY8 can be used to analyze flow capacity and overtopping flow for roadway culverts
• Understand how to evaluate different culvert options using HY8.
• Understand how minimum and maximum cover can impact the selection of culvert size and material
• Understand the importance of limiting upstream headwater on culverts, even in high fill situations
• Understand the need for erosion protection on both the inlet and outlet of a culvert
• Understand how to evaluate the service life for different pipe materials.
There are no special prerequisites.
This course is intended as an introduction to design of culverts under roadways and therefore the intended audience includes engineers designing culverts. It also includes transportation works officials responsible for construction or maintenance of culverts.
COURSE SUMMARY:
This course will provide the user with a basic understanding the material options commonly used for roadway culverts and how to use the FHWA software package HY8 to evaluate culverts. Improper selection of culvert materials, inlet configurations or other design parameters can result in premature failure of culverts or the inability to convey the design flows. Proper material selection is also important to ensure the selected material will provide the necessary service life for the facility. This course will discuss appropriate sizing criteria for a culvert, including end sections and maximum allowable headwater.
